FIG. 1 depicts a conventional method 10 for fabricating a magnetoresistive sensor in magnetic recording technology applications. The method 10 typically commences after a conventional magnetoresistive or tunneling magnetoresistive (TMR) stack has been deposited. The conventional read sensor stack typically includes an antiferromagnetic (AFM) layer, a pinned layer, a nonmagnetic spacer layer, and a free layer. In addition, seed and/or capping layers may be used. The conventional magnetoresistive stack resides on an underlayer, which may be a substrate.
The conventional method 10 commences by providing a conventional hard mask layer and a photoresist mask, via step 12. The conventional hard mask layer is typically a material such as SiC or diamond-like carbon (DLC). The conventional photoresist mask has the desired pattern, which is transferred to the conventional hard mask layer. The conventional photoresist mask covers the region from which the conventional magnetoresistive sensor is to be formed, as well as a portion of the transducer distal from the sensor. However, part of the device region adjoining the magnetoresistive sensor is left uncovered.
A conventional hard mask is defined from the conventional hard mask layer, via step 14. Step 14 includes transferring the pattern from the conventional photoresist mask, for example through a reactive ion etch (RIE). The photoresist mask may also be removed in step 14.
The magnetoresistive structure is defined, via step 16. Step 16 typically includes ion milling the transducer. Thus, the exposed portion of the magnetoresistive stack is removed. The magnetoresistive structure being defined may be a magnetoresistive sensor for a read transducer.
The hard bias material(s), such as CoPt, are deposited, via step 18. In addition, seed and/or capping layers may be provided in step 18. The hard bias material(s) and other layers are deposited while the conventional hard mask is in place. In addition, a shallow mill may be performed as part of providing the hard bias structure. A capping layer may be deposited after the shallow ion mill is completed. The capping layer typically includes a noble metal such as Ru, Ta, and/or Rh.
A chemical mechanical planarization (CMP) is performed, via step 20. This CMP aids in removing the hard bias materials above the hard mask and planarizes the top surface of the transducer. The hard mask may then be removed, for example via a reactive ion etch (RIE), via step 22. An additional planarization is performed, via step 24. The stripe height of the sensor is then defined, via step 26. Note that in some instances, the stripe height may be defined in step 26 prior to the steps 12-24 used at least in part to define the magnetoresistive sensor. An insulator such as aluminum oxide is deposited on the transducer, via step 28.
FIG. 2 depicts an ABS view of a conventional transducer 50 fabricated using the conventional method 10. For clarity, FIG. 2 is not to scale. A TMR sensor 54 residing on a substrate 52 is shown. Also shown are hard bias 56 and 58. The TMR junction 54 has inboard and outboard junction angles, α and β. The inboard junction angle, α, is closer to the center of the substrate on which the junction 54 is fabricated than the outboard junction angle β. Also shown is insulator 60 and 62 provided in step 28.
Although the conventional method 10 allows the conventional transducer 50 to be fabricated, there are several drawbacks. The conventional method 10 still results in within wafer variations that are greater than desired. For example, the onboard junction angle, α, is typically different from the outboard junction angle, β. This difference may be greater than the desired α. Further, portions of the read sensor stack may be left in the field regions after the read sensor is defined in the stripe height and track width directions. There may also be variations in the height of the hard bias structure above the conventional TMR sensor 54. The insulator 60 and 62 provided on the transducer 50 in step 28 may have a height that varies to a greater degree than desired. It may also be typically difficult to control the CMPs performed in steps 20 and 24. Thus, some portion of the hard bias materials 56 and 58 may be depleted of certain constituents, such as Co. Further, the slurry used for the CMPs performed in steps 20 and 24 may result in corrosion of underlying metal layers, particularly Co depleted hard bias materials 56 and 58. Thus, fabrication of the conventional read transducer 50 is desired to be improved.
Accordingly, what is needed is a system and method for improving the fabrication of a magnetic recording read transducer.